Acquired immune deficiency syndrome (AIDS) is an immunodeficiency disease caused by human immunodeficiency virus (HIV) that infects and destroys the immune cells, which leads to acquired immunodeficiency. AIDS surpasses malaria and tuberculosis in deaths worldwide. According to the report from the UNAIDS (the joint United Programme on HIV/AIDS) in November, 2007, the number of infected people was estimated to be 33 million with deaths of more than 2 million only in 2007 (“2007 AIDS epidemic update” 19 Nov. 2007).
Drug therapy for HIV requires accurate and continuous drug use. This is because the effective drug level in the blood needs to be kept constant in order to suppress viral proliferation, and missing doses or time lag in taking doses could cause emergence or proliferation of drug-resistant viruses (see Non-Patent Reference 1). Thus, in order to ensure successful anti-HIV therapy, good patient adherence, that is, patient's active involvement in the decision-making process in the therapeutic approach and carrying out that therapeutic approach on patient's own initiative, is important (see Non-Patent Reference 2).
Although current mainstay for drug treatment is multi-drug therapy (HAART) that employs a combination of multiple drugs, there has been a problem of undesirable drug switch due to emergence of drug-resistant virus and side-effects.
Recently, 4′-ethynyl-2′,3′-didehydro-3′-deoxythymidine (4′-ethynyl d4T) was developed as a new active substance for drugs that solve this problem (see Patent Reference 1), whose clinical trial is expected to commence in the United States in 2008. 4′-ethynyl d4T is also effective against multidrug-resistant viruses, and supposed to be highly safe with lower mitochondrial toxicity and thus expected to facilitate long-term drug use and continuous adherence.
Production of 4′-ethynyl d4T, however, has problems in that conventional synthetic methods (see Patent Reference 1 and Non-Patent Reference 3) require a number of synthetic steps, that their production cost is high, and that they are ill-suited to mass production.
[Patent Reference 1] Japanese Laid-Open Patent Application No. 2006-528972.
[Non-Patent Reference 1] Paterson D, et al., 6th Conference on Retroviruses and Opportunistic Infections, Chicago, III, 1999.
[Non-Patent Reference 2] Yoshino, The Journal of Therapy, Vol. 88, No. 12 (2006.12), p. 2903-2907.
[Non-Patent Reference 3] Maddaford, et al., Synthesis, 2007, No. 9, p. 1378-1384.